Impact of metformin on the therapeutic effect of radiotherapy

To explore the effect of metformin on therapeutic outcomes in cancer patients undergoing radiotherapy. A literature search of the electronic databases was conducted to retrieve articles that investigated the effect of metformin on radiotherapy. Timeframe of electronic search ranged from the inception of each database to May 2020. These databases include PubMed, Embase and Scopus. From an initial search of 142 articles, and after the removal of duplicates as well as applying the inclusion and the exclusion criteria, 20 articles were finally included in this systematic review. Results from the reviewed clinical studies showed promising therapeutic effect of the combination of metformin with radiotherapy. Metformin has promising therapeutic effects as an adjuvant with radiotherapy. The use of metformin as an adjuvant with radiotherapy should be treated with caution, as further studies investigating its optimal dose as well as molecular mechanisms are still needed.